• Title/Summary/Keyword: Charge storage density

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The Effects of Ag Addition on the Electrode Properties of Hydrogen Storage Alloys (Zr계 수소저장합금의 전극특성에 미치는 은 첨가의 영향)

  • Noh, Hak;Jeong, So-yi;Choi, Seung-jun;Choi, Jeon;Seo, Chan-yeol;Park, Choong-Nyeon
    • Journal of Hydrogen and New Energy
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    • v.8 no.3
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    • pp.137-141
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    • 1997
  • The effects of Ag addition to Zr-based hydrogen storage alloys ($Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.4}$, $Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.3}Cr_{0.1}$ and $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.3}Fe_{0.1}$) on the electrode properties were examined. Ag-free and Ag-added Ze-based alloys were prepared by arc melting, crushed mechanically, and subjected to the electrochemical measurement. In $Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.4}$ alloy, 0.08 wt% Ag addition to the alloy improved the activation rate. Also Ag addition improved both activation property and discharge capacity in $Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.3}Cr_{0.1}$. For these Ag-added alloys, discharge capacities with the change of charge-discharge current density(10mA, 15mA and 30mA) are almost constant. Showing very high rate capability, discharge capacity of $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.3}Fe_{0.1}$ alloy increased by Ag addition to the alloy. When the amount of Ag addition in $Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.4}$ alloy increased too much, the electrode properties became worse. Unveiling mechanism of effect of Ag addition is now progressing in our laboratory.

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Energy Management and Performance Evaluation of Fuel Cell Battery Based Electric Vehicle

  • Khadhraoui, Ahmed;SELMI, Tarek;Cherif, Adnene
    • International Journal of Computer Science & Network Security
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    • v.22 no.3
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    • pp.37-44
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    • 2022
  • Plug-in Hybrid electric vehicles (PHEV) show great potential to reduce gas emission, improve fuel efficiency and offer more driving range flexibility. Moreover, PHEV help to preserve the eco-system, climate changes and reduce the high demand for fossil fuels. To address this; some basic components and energy resources have been used, such as batteries and proton exchange membrane (PEM) fuel cells (FCs). However, the FC remains unsatisfactory in terms of power density and response. In light of the above, an electric storage system (ESS) seems to be a promising solution to resolve this issue, especially when it comes to the transient phase. In addition to the FC, a storage system made-up of an ultra-battery UB is proposed within this paper. The association of the FC and the UB lead to the so-called Fuel Cell Battery Electric Vehicle (FCBEV). The energy consumption model of a FCBEV has been built considering the power losses of the fuel cell, electric motor, the state of charge (SOC) of the battery, and brakes. To do so, the implementing a reinforcement-learning energy management strategy (EMS) has been carried out and the fuel cell efficiency has been optimized while minimizing the hydrogen fuel consummation per 100km. Within this paper the adopted approach over numerous driving cycles of the FCBEV has shown promising results.

Improvement of Energy Density in Supercapacitor by Ion Doping Control for Energy Storage System (에너지 저장장치용 슈퍼커패시터 이온 도핑 제어를 통한 에너지 밀도 향상 연구)

  • Park, Byung-jun;Yoo, SeonMi;Yang, SeongEun;Han, SangChul;No, TaeMoo;Lee, Young Hee;Han, YoungHee
    • KEPCO Journal on Electric Power and Energy
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    • v.5 no.3
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    • pp.209-213
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    • 2019
  • Recently, demand for high energy density and long cycling stability of energy storage system has increased for application using with frequency regulation (F/R) in power grid. Supercapacitor have long lifetime and high charge and discharge rate, it is very adaptable to apply a frequency regulation in power grid. Supercapacitor can complement batteries to reduce the size and installation of batteries. Because their utilization in a system can potentially eliminate the need for short-term frequent replacement as required by batteries, hence, saving the resources invested in the upkeep of the whole system or extension of lifecycle of batteries in the long run of power grid. However, low energy density in supercapacitor is critical weakness to utilization for huge energy storage system of power grid. So, it is still far from being able to replace batteries and struggle in meeting the demand for a high energy density. But, today, LIC (Lithium Ion Capacitor) considered as an attractive structure to improve energy density much more than EDLC (Electric double layer capacitor) because LIC has high voltage range up to 3.8 V. But, many aspects of the electrochemical performance of LIC still need to be examined closely in order to apply for commercial use. In this study, in order to improve the capacitance of LIC related with energy density, we designed new method of pre-doping in anode electrode. The electrode in cathode were fabricated in dry room which has a relative humidity under 0.1% and constant electrode thickness over $100{\mu}m$ was manufactured for stable mechanical strength and anode doping. To minimize of contact resistance, fabricated electrode was conducted hot compression process from room temperature to $65^{\circ}C$. We designed various pre-doping method for LIC structure and analyzing the doping mechanism issues. Finally, we suggest new pre-doping method to improve the capacitance and electrochemical stability for LIC.

Comparative Analysis of SOC Estimation using EECM and NST in Rechargeable LiCoO2/LiFePO4/LiNiMnCoO2 Cells

  • Lee, Hyun-jun;Park, Joung-hu;Kim, Jonghoon
    • Journal of Electrical Engineering and Technology
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    • v.11 no.6
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    • pp.1664-1673
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    • 2016
  • Lithium rechargeable cells are used in many industrial applications, because they have high energy density and high power density. For an effective use of these lithium cells, it is essential to build a reliable battery management system (BMS). Therefore, the state of charge (SOC) estimation is one of the most important techniques used in the BMS. An appropriate modeling of the battery characteristics and an accurate algorithm to correct the modeling errors in accordance with the simplified model are required for practical SOC estimation. In order to implement these issues, this approach presents the comparative analysis of the SOC estimation performance using equivalent electrical circuit modeling (EECM) and noise suppression technique (NST) in three representative $LiCoO_2/LiFePO_4/LiNiMnCoO_2$ cells extensively applied in electric vehicles (EVs), hybrid electric vehicles (HEVs) and energy storage system (ESS) applications. Depending on the difference between some EECMs according to the number of RC-ladders and NST, the SOC estimation performances based on the extended Kalman filter (EKF) algorithm are compared. Additionally, in order to increase the accuracy of the EECM of the $LiFePO_4$ cell, a minor loop trajectory for proper OCV parameterization is applied to the SOC estimation for the comparison of the performances among the compared to SOC estimation performance.

Preparation and Electrical properties of the PLT(28) Thin Film (PLT(28) 박막의 제작과 전기적 특성에 관한 연구)

  • 강성준;정양희
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.11a
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    • pp.784-787
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    • 2002
  • We prepared the PLT(28) thin film by using sol-gel method and investigated the structure and electrical properties of the film. With the XRD and AFM analyses, it is found that PLT(28) thin film annealed at 6sot has a complete perovskite structure and its surface roughness is about 22$\AA$. We prepared PLT(28) thin film on the Pt/TiO$_{x}$SiO$_2$/Si substrate, in which the specimen has a planar capacitor structure, and analyzed the electrical properties of PLT(28) thin film. In result, PLT(28) thin film has a paraelectric phase and its dielectric constant and loss tangent at 10kHz are 761 and 0.024, respectively. Also, the storage charge density and leakage current density of PLT(28) thin film at W are 134fC/$\mu$m2 and 1.01 $\mu$A/cm2, respectively. As a result of this, we concluded that the PLT(28) thin film is a promising material to be used as a capacitor dielectrics for next generation DRAM.M.

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Study on the Electrolyte Added Chlorosulfuric Acid for All-vanadium Redox Flow Battery (바나듐 레독스 흐름 전지용 전해액으로 클로로황산 첨가에 관한 연구)

  • OH, YONG-HWAN;LEE, GEON-WOO;RYU, CHEOL-HWI;HWANG, GAB-JIN
    • Journal of Hydrogen and New Energy
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    • v.27 no.2
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    • pp.169-175
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    • 2016
  • The electrolyte added the chlorosulfuric acid ($HSO_3Cl$) as an additive was tested for the electrolyte in all-vanadium redox flow battery (VRFB) to increase the thermal stability of electrolyte. The electrolyte property was measured by the CV (cyclic voltammetry) method. The maximum value of a voltage and current density in the electrolyte added $HSO_3Cl$ was higher than that in the electrolyte non-added $HSO_3Cl$. The thermal stability of the pentavalent vanadium ion solution, which was tested at $40^{\circ}C$, increased by adding $HSO_3Cl$. The performances of VRFB using the electrolyte added and non-added $HSO_3Cl$ were measured during 30 cycles of charge-discharge at the current density of $60mA/cm^2$. An average energy efficiency of the VRFB was 72.5%, 82.4%, and 81.6% for the electrolyte non-added $HSO_3Cl$, added 0.5 mol of $HSO_3Cl$, and added 1.0 mol of $HSO_3Cl$, respectively. VRFB using the electrolyte added $HSO_3Cl$ was showed the higher performance than that using the electrolyte non-added $HSO_3Cl$.

Single Carrier Spectroscopy of Bisolitons on Si(001) Surfaces

  • Lyo, In-Whan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.13-13
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    • 2010
  • Switching an elementary excitation by injecting a single carrier would offer the exciting opportunity for the ultra-high data storage technologies. However, there has been no methodology available to investigate the interaction of low energy discrete carriers with nano-structures. In order to map out the spatial dependency of such single carrier level interactions, we developed a pulse-and-probe algorithm, combining with low temperature scanning tunneling microscopy. The new tool, which we call single carrier spectroscopy, allows us to track the interaction with the target macrostructure with tunneling carriers on a single carrier basis. Using this tool, we demonstrate that it is possible not only to locally write and erase individual bi-solitons, reliably and reversibly, but also to track of creation yields of single and multiple bi-solitons. Bi-solitons are pairs of solitons that are elementary out-of-phase excitations on anti-ferromagnetically ordered pseudo-spin system of Si dimers on Si(001)-c(42) surfaces. We found that at low energy tunneling the single bisoliton creation mechanism is not correlated with the number of carriers tunneling, but with the production of a potential hole under the tip. An electric field at the surface determines the density of the local charge density under the tip, and band-bending. However a rapid, dynamic change of a field produces a potential hole that can be filled by energetic carriers, and the amount of energy released during filling process is responsible for the creation of bi-solitons. Our model based on the field-induced local hole gives excellent explanation for bi-soliton yield behaviors. Scanning tunneling spectroscopy data supports the existence of such a potential hole. The mechanism also explains the site-dependency of bi-soliton yields, which is highest at the trough, not on the dimer rows. Our study demonstrates that we can manipulate not just single atoms and molecules, but also single pseudo-spin excitations as well.

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Variations in electrode characteristics through simplification of phosphorus-doped NiCo2O4 electrode manufacturing process (인이 도핑된 NiCo2O4 전극 제조 공정의 간소화를 통한 전극 특성의 변화)

  • Seokhee-Lee;Hyunjin Cha;Jeonghwan Park;Young Guk Son;Donghyun Hwang
    • Journal of Surface Science and Engineering
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    • v.56 no.5
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    • pp.299-308
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    • 2023
  • In this study, phosphorus (P)-doped nickel cobaltite (P-NiCo2O4) and nickel-cobalt layered double hydroxide (P-NiCo-LDH) were synthesized on nickel (Ni) foam as a conductive support using hydrothermal synthesis. The thermal properties, crystal structure, microscopic surface morphology, chemical distribution, electronic state of the constituent elements on the sample surface, and electrical properties of the synthesized P-NiCo2O4 and P-NiCo-LDH samples were analyzed using thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The P-NiCo2O4 electrode exhibited a specific capacitance of 1,129 Fg-1 at a current density of 1 Ag-1, while the P-NiCo-LDH electrode displayed a specific capacitance of 1,012 Fg-1 at a current density of 1 Ag-1. When assessing capacity changes for 3,000 cycles, the P-NiCo2O4 electrode exhibited a capacity retention rate of 54%, whereas the P-NiCo-LDH electrode showed a capacity retention rate of 57%.

Facile Chemical Growth of Cu(OH)2 Thin Film Electrodes for High Performance Supercapacitors (간단한 화학적 합성을 통한 고성능 슈퍼캐패시터용 수산화 구리 전극)

  • Patil, U.M.;Nam, Min Sik;Shinde, N.M.;Jun, Seong Chan
    • KEPCO Journal on Electric Power and Energy
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    • v.1 no.1
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    • pp.175-180
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    • 2015
  • A facile soft chemical synthesis route is used to grow nano-buds of copper hydroxide [$Cu(OH)_2$] thin films on stainless steel substrate[SS]. Besides different chemical methods for synthesis of $Cu(OH)_2$ nanostructure, the chemical bath deposition (CBD) is attractive for its simplicity and environment friendly condition. The structural, morphological, and electro-chemical properties of $Cu(OH)_2$ thin films are studied by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurement techniques. The results showed that, facile chemical synthesis route allows to form the polycrystalline, granular nano-buds of $Cu(OH)_2$ thin films. The electrochemical properties of $Cu(OH)_2$ thin films are studied in an aqueous 1 M KOH electrolyte using cyclic voltammetry. The sample exhibited supercapacitive behavior with $340Fg^{-1}$ specific capacitance. Moreover, electrochemical capacitive measurements of $Cu(OH)_2/SS$ electrode exhibit a high specific energy and power density about ${\sim}83Wh\;kg^{-1}$ and ${\sim}3.1kW\;kg^{-1}$, respectively, at $1mA\;cm^{-2}$ current density. The superior electrochemical properties of copper hydroxide ($Cu(OH)_2/SS$) electrode with nano-buds like structure mutually improves pseudocapacitive performance. This work evokes scalable chemical synthesis with the enhanced supercapacitive performance of $Cu(OH)_2/SS$ electrode in energy storage devices.

Sodium Sulfur Battery for Energy Storage System (대용량 에너지 저장시스템을 위한 나트륨 유황전지)

  • Kim, Dul-Sun;Kang, Sungwhan;Kim, Jun-Young;Ahn, Jou-Hyeon;Lee, Chang-Hui;Jung, Keeyoung;Park, Yoon-Cheol;Kim, Goun;Cho, Namung
    • Journal of the Korean Electrochemical Society
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    • v.16 no.3
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    • pp.111-122
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    • 2013
  • Sodium sulfur (NAS) battery is a high energy storage system (ESS). These days, as the use of renewable green energy like wind energy, solar energy and ocean energy is rapidly increasing, the demand of ESS is increasing and NAS battery is considered to be one of the most promising ESS. Since NAS battery has a high energy density(3 times of lead acid battery), long cycle life and no self-charge and discharge, it is a good candidate for ESS. A NAS battery consists of sulfur as the positive electrode, sodium as the negative electrode and ${\beta}$"-alumina as the electrolyte and a separator simultaneously. Since sulfur is an insulator, carbon felt should be used as conductor with sulfur and so the composition and property of the cathode could largely influence the cell performance and life cycle. Therefore, in this paper, the composition of NAS battery, the property of carbon felt and sodium polysulfides ($Na_2S_x$, intermediates of discharge), and the effects of these factors on cycle performance of cells are described in detail.